MTS Advantage Screw Action Grip - Manual (Page 14)

MTS Advantage™ Screw Action Grips Introduction 14
The grips have serrated knobs that are used to manually apply an initial
gripping force on the specimen. For grips rated above 100 N (25 lbf), once
the specimen is hand tightened into the grips, a torque wrench is used to
ensure there is adequate clamping. The torque wrench also compresses a
compliant compression puck to ensure the face surfaces follow specimen
deformation during elongation. The tensile load pulls the face surfaces,
forcing them to pivot around a pin. The pivoting reduces the clamping
pressure at the top of the face surfaces and increases it at the bottom of the
face surfaces. Rotation of the face surfaces reduces the likelihood of a failure
in the high stress area of the clamp.